I use it too on my 600, but you really need to figure out your max ISO. Meaning, take some test shots at various high ISO and see what max you want for it. Its a nice tool, but in some situations I have had it overexpose and underexpose. Yes you can fix in post-processing and I have never had it blow a shot, I just want to get it right in the camera to decrease my post-processing time.
But in short, use it, it will be a little different at first but you will get comfortable with it.